Heat actuated device



June 27, 1944.

W..S. LANDON HEAT AGTUATED DEVICE Filed June 8. 1940 Patented June 27, 1944 HEAT ACTUATED DEVICE Walter S. Landon, Detroit, Mich., asaignor to Detroit Lubricator Company, Deti-olt, Mich., a corporation of Michigan Application June s, 1940, seriai'No. 339,427 iolaims. (o1. en -z3) This invention relates generally to heat actuvated power elements and more particularly to a heater for actuating a bimetallic member.

An object of this invention is to provide a new and novel heater which will readily adjust itself to the contour of the heat actuated element.

A further object is to provide a construction for making the contour following heater flexible and resilient. y

A further object is to provide a heater having a high rate of increase and decrease in temperature upon energization and deenergization.

A further object is to provide a new and novel heater which is easily and economically manuiactured.

The invention consists in the improved construction and combination of parts, to be more fully described hereinafter, and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawing, to be taken as a part of this specification, there is clearly and fully illustrated a preferred embodiment of this invention, in which drawing:

Figure 1 is a view in elevation of a heat actuated bimetallic power element embodying the invention; v

Fig. 2 is a view substantially along the line 2-2 of Fig. 1 looking in the direction ci' the arrows;

Fig. 3 is a view of certain of the parts of the heater element separated from each other and each being in front elevation;

Fig. 4 is an exploded view of certain of the parts of the heater element in end-elevation;

Fig. 5 is an enlarged sectional view showing the method of securing the parts together and o! connecting the terminals of the resistance coil, and

Fig. 6 is a view in bled heater element.

Referring to the drawing by characters oi reference, the numeral I designates generally the heat actuated bimetallic power element comprising a heater element 2, positioned within and conforming to the inside contour of a bimetallic element 3. The bimetallic element 3 comprises a strip of bimetal which has one end portion 4 rigidly secured, as at 5, to a suitable supporting member 6 and the bimetal is then bent into the shape of a cylinder 1 having its longitudinal axes extending perpendicular to the length of the bimetal and the end portion 8 opposite to the end portion 4 is bent to extend radially outward from the cylinder 1 which has a narrow slit or opening 3 formed between the end portion 4 and the perspective of the assemr the heater element` 2.

intersection of the end portion 3 and cylinder 1.

The heater element 2 comprises a pair of elongated corrugated iiexible mica strips III, II having at one end portion thereof portions I2, I3 respectively of increased width, The strips III, II are congruent and have apertures I4, I5, respectively, at one end portion and have a plurality of apertures I8, I1 and I8, I9 through the end portions I2, I3. The strips I0, II at the end portions I2, I3 have recesses 20, 2|, respectively, which are of a width substantially equal to the width of the bimetallic element 3 and which, when in cooperative position therewith, receive the element 3 and hold the element 2 in correct relative position. An elongated flexible mica strip 22 is similar to strips I0, II but has a width and length somewhat greater than strips II), II. The strip 22 also has a portion 23 oi.' increasedwidth similar to portions I2 and I3 and of equal size. The portion 23 also has a recess 24 and a pair of apertures 25 which are congruent with recesses 20, 2I and apertures I1 and I9. The strips I0, II and 22 are-placed in juxtaposition with the apertures I1, I9 and 25 and recesses 20, 2i and `24 in alignment. A pair of relatively heavier non-flexible mica pieces 26, 21 which have apertures 28, 29, respectively, and recesses 30, 3l, respectively, are congruent with the enlarged width portions I2, I3 and 23 and are placed so that piece 26 is against strip I0 and piece 21 is against strip 22. The recesses 20, 2|, 24, 30 and 3| act toprovide the strips III, II and 22 and pieces 26 and 21 respectively with extending legs which are adapted to straddle the bimetallic strip of Hollow rivets 32, 33 extend through the apertures Il, I9, 25, 28 and 23 and have their head portions riveted over tightly against pieces 28 and 2 so that the strips I0, II and 22 are held firmly together and to the pieces 26 and 21. The strips I0, II and 22 are preferably fabricated from corrugated mica but due to the tightness with which the portions I2,

I3 and 23 are held together by the rivets and pieces 26 and 21 they may be relatively at leaving only the normal width portions of strips I0, II and 22 corrugated.

The strips I8 and II serve to carry lthe resistance heater unit 34 which is made from a strip of resistance wire 35. One end of the wire 35 is secured tightly about the rivet 32. The wire then passes through one of the apertures 28, along the space intermediate the piece 26 and strip I8, through one of the apertures I6 up between strips II) and II and then ythrough aperture I5. After passing through'aperture I5 the wire 35 is wound helically downward around the strips I and II toward the portions I2 and I3 and when the wire 35 substantially reaches p0rtions I2 and I3, the wire 35 is brought through the other of the apertures I8 and I6 after which it passes between piece 26 and strip I0 and then up through the other of the apertures 28 and the end ls secured tightly to the rivet 33. Lead wires 36, 31 are secured within` the hollow interior of rivets 32, 33, respectively, and serve to connect the ends of the resistance heating unit 34 to a suitable source of electrical energy.

After assembly of the heater element 2 it is placed within the cylinder 1 of the bimetallic element 3 with the strip 22 adjacent and substantially conforming to the contour of the bimetal, and the recesses 20, 2|, 24, 3II and 3I receive a portion of the cylinder 1 adjacent the end portion 4. Prior tothe initial bending of the corrugated strips I, Il and 22 they are relatively stiff and rigid. This is particularly advantageous for winding the unit 34 because the strips I0 and Il are then innately strong enough to allow the wire 35 to be wound easily thereon. After initial bending of the mica, however, the rigidity of the strips changes and the strips; I 0, II and 22 become resiliently exible so that after being positioned within the cylinder 1 the strips will adjust themselves to the inside contour of the cylinder and due to the resiliency will tend to open against the inside of the cylinder 1 and as the cylinder 1 flexes under the influence of the heater element 2 the flexible strips I0, I I and 22 will continue to flex and remain in intimate contact therewith.

The operation of the heat actuated power element I is as follows: The lead wires 36, 31 are lconnected to a suitable source of electrical energy which is controlled in any desired manner, as by a switch (not shown), so .that the heater unit 34 may be energized ordeenergized as desired. Upon energization of the heater 34 the cylinder 1 of the bimetallic element 3 is heated which tends to open up the slit 9 or unwind the cylinder 1 so that the lip or end portion 8 of element 3 is moved upward thereby to actuate any desired reciprocally movable member (not shown). Upon opening of the switch (not shown), the heater unit 34 is deenergized and the bimetallic element 3 cools thereby moving portion 8 back to its original position and reciprocating said movable member (not shown) back to its original position.

It may now be seen thatl there is set forth and fully disclosed herein a heat actuated element which is simple and economical of construction and suitable for manufacture in large quantities. The heater unit 34 is amply protected from "shorting against the bimetal of cylinder 1 and is so constructed that it stays in intimate heat transfer relationship with the cylinder 1 irrespective of the movement of cylinder 1 due to change in its temperature, and the mass of the heater element 2 is small so that immediately subsequent to deenergization of the unit 34, the element 2 will cool thereby allowing the cylinder 1 to quickly cool and move end portion 8 to its original or cold position` The particular construction in which the heater 34 is wound helically along the longitudinal axes of the strips III and I I provides a heater in which` the resistance wires are flexed as little as possible, there being in the present construction a single wire. that portion of the wire 35 running longitudinally intermediate the strips I0 and Il, which exes any appreciable amount and this portion is not drawn tightly between the apertures I5 and I6.

What I claim and desire to secure by Letters Patent of the United States is:

l. A flexible electric heating element comprising a pair of corrugated mica strips in opposed facing relation, and a resistance wire having one portion extending transverse to said corrugations and between said strips and having another portion binding said strips to each other by a multiplicity of spaced turns wound around both of said strips together and substantially parallel to the corrugations so that said strips hold said one portion frictionally in position therebetween.

2. A flexible electric heating element comprising a pair of corrugated mica strips in opposed facing relation, a resistance wire having one portion extending transverse to said corrugations and between said strips and having another portion binding said strips to each other by a multiplicity of spaced turns wound around both of said strips together and substantially parallel to the corrugations so that said strips hold said one portion frictionally in position therebetween, and a corrugated mica strip having its corrugations parallel to the corrugations of said strips, said strip being secured at one end to one end of and overlying one face of said strips and having a width greater than said strips thereby to protect the ends of said turns.

3. A heat actuated power means comprising a bimetallic power element having a substantially cylindrical portion, a flexible resilient supporting member of electric insulating sheet material positioned Within and held solely by friction against circumferential movement relative to said cylindrical portion, said member conforming automatically by its innate resiliency to the contour of said element portion irrespective of contraction or expansion thereof due to temperature change, and a resistance wire wound upon and bodily removable with said member and acting upon the passage of an electric current therethrough to heat said power element.

4. A heat actuated power means comprising a bimetallic power element having a substantially cylindrical portion, a flexible resilient supporting member of electric insulating sheet material positioned within and held solely by friction against circumferential movement relative to said cylindrical portion, said member conforming automatically by its innate resiliency to the contour of said element portion irrespective of contraction or expansion thereof due to temperature change, a resistance wire wound upon and bodily removable with said member and acting upon the passage of an electric current therethrough to heat said power element, and spaced legs on one end portion of said supporting member and laterally engageable with the side edges of said cylindrical portion to hold said supporting member against unintentional lateral displacement.

5. A heat actuated power means comprising, a bimetallic power element having a substantially cylindrical portion, an electric insulating sheet material positioned in and substantially conforming to the contour of said portion, said material being transversely corrugated for flexibility and acting due to its innate resiliency to conform with the contour of said portion irrespective of contraction or expansion thereof due to temperature change, a resistance wire on said member and having its turns running substantially longitudinally of the corrugations, a backing member of electric insulating sheet material positioned intermediate said portion and said sheet material and secured to one side of said member and overlying said wire, and projecting portions on said sheet material for receiving therebetween said element thereby to position said material within said cylindrical portion.

6. A heat actuated power means comprising, a bimetallic power element having a substantially cylindrical portion, an electric insulating sheet material positioned in and substantially conforming to the contour of said portion, said material being transversely corrugated for flexibility and acting due to its innate resiliency to conform with the contour of said portion irrespective of contraction or expansion thereof due to temperature change, a resistance wire on said member and having its turns running substantially longitudinally of the corrugations, and a backing member of electric insulating sheet material positioned intermediate said portion and said sheet material and secured to one side of said member and overlying said wire, said material having at one end portion a portion of increased width, said increased width portion having a recess therein for receiving said element thereby to position said material within said portion.

7. A heat actuated power element comprising a first elongated ilexible strip, said striphaving an aperture therethrough at one end portion thereof and having a plurality of apertures therethrough at the other end portion thereof, a second elongated exible strip, said second strip having an aperture therethrough at one end portion thereof and having a plurality of apertures therethrough at the other end portion thereof, said strips being placed in juxtaposition with the apertures of said one strip in alignment with'the apertures of said second strip. a resistance wire passing through one of said plurality of apertures in one ofl said strips, said wire passing longitudinally between said strips and through said one end aperture in one of said y strips, said wire being wound in a spiral about said strips from said one end to said other end,

said Wire then passing through the other of said plurality of apertures, a third lelongated flexible strip placed in juxtaposition with one of said strips, means tightly securing together said third strip and said other end of said iirst and said second strips, said securing means also acting as terminals for the ends of said resistance wire, and a heat actuated power element having a cylindrical portion, said strips having at said other end a slot equal in width to the longitudinal dimension of said cylindrical portion, said strips being positioned within and conforming to the inside contour of said cylindrical portion and positioned with said third strip adjacent said element, said slot receiving said cylindrical portion for positioning of said strips.

WALTER S. LANDON. y 

